GSTM1 and hereditary spherocytosis: In most of the cases described, SCT was, in fact, associated either with the coexistence of other Hb mutations (for example, HbS-Antilles; Hb-Quebec-Chori; HbS-Oman; Hb-Jamaica) or with other red blood cell defects (spherocytosis, pyruvate kinase deficiency, etc.).